1. Field of the Invention
The present invention relates to an electrostatic latent image-developing toner for forming a monochrome image or a full color image, and also concerns an image-forming method for forming images with such a toner.
2. Description of the Related Art
In the field of electrophotography, it is an effective method to miniaturize the toner particle size in order to obtain high image quality. However, the miniaturization of the toner particle size causes degradation in the cleaning properties and the electrification properties. Moreover, in order to improve the fluidity that deteriorates due to the miniaturization of the toner particle size, a little excessive fluidizing agent is added; however, an increased amount of the fluidizing agent also causes degradation in the cleaning properties and the electrification properties.
With respect to techniques proposed to improve the cleaning properties, for example, Japanese Patent Application (JPA) Laid-Open No. 76406/1996 disclosed that organic fine particles made of polyvinylidene fluoride are added to the toner surface, or JPA Laid-Open No. 160165/1995 discloses that zinc stearate is added to the toner surface.
U.S. Pat. No. 4,933,253, U.S. Pat. No. 4,943,505 and JPA Laid-Open No.186876/1985 have proposed techniques in which fine particles of methylmethacrylate or copolymer particles thereof with styrene are added to the toner surface as an cleaning-assist agent, or U.S. Pat. No. 4,187,329 has proposed a technique in which fine particles of a fluorine compound, typically Teflon, is added to the toner surface as a cleaning-assist agent.
Furthermore, for example, in a technique proposed by U.S. Pat. No. 4,883,736, alkyl alcohol with a long chain is added to the toner surface.
With respect to inorganic fine particles, for example, U.S. Pat. No. 5,759,731 has proposed a method in which a metal oxide such as strontium titanate is added to the toner surface as a polishing agent for a photosensitive member.
However, in the above-mentioned method for adding a metal salt of fatty acid such as zinc stearate to the toner surface, the cleaning properties improve, but an increased amount of addition to the toner raises a problem in which the electrification properties of toner deteriorates extremely.
With respect to metal oxides such as alkyl alcohol with a long chain and strontium titanate, the adverse effect is not as serious as the above-mentioned metal salt of fatty acid. The addition thereof to the toner surface, however, tends to cause degradation of the electrification properties of toner.
With respect to the fine particles of methylmethacrylate or a copolymer thereof with styrene or fine particles of a fluorine compound, the addition thereof to the toner surface gives a little improving effect to the cleaning properties. But, it gives little effect, in particular, to prevent black spots on the photosensitive member caused by toner components.